Numerous sites, such as universities, amusement parks, shopping centers , malls, hospitals, government installations, and industrial facilities have transitways such as roadways, walks or other open areas from which it is desirable to prevent the transit of vehicular traffic. However, it is usually imperative that authorized vehicles and particularly emergency vehicles be allowed ready access to such areas via these transitways. For example, a university may wish to prohibit vehicular traffic through campus, yet must allow fire or other emergency vehicles to enter the central portion of campus in an expedient manner. Ordinarily, barriers such as chains or gates are erected, there are, however, numerous disadvantages to such solutions. Gates and chains impede pedestrian traffic and pose a safety problem to pedestrians as well. Moreover, the locks or other devices which secure these structures may become frozen in the winter or corrode, thus being rendered inoperable in an emergency. Additionally, if a lock is used, keys must be provided to fire and police personnel; invariably locks are changed without providing new sets of keys, resulting in a possibly life-threatening delay. Similarly, portable wooden barricades are an ineffective solution, since two persons are required in order to erect and move them. Portable wooden barricades suffer from a disadvantage in that they may be moved by any persons, thereby lacking any security.
As an alternative to gates and chains, rows of fixed, spaced posts or bollards may be installed. Fixed bollards limit access by vehicles and allow pedestrians free access, however, their permanence creates an unacceptable barrier to emergency vehicles and an inconvenience to maintenance or other authorized vehicles. In some cases, certain bollards are designed to be removable, however, these designs invariably expose a locking or sliding portion to the elements, leading to the corroded or frozen condition mentioned above. For example, depressible bollards of the type described in U.S. Pat. Nos. 4,576,508 and 4,715,742, both issued to Dickinson, may freeze in either the upright or depressed position, despite whatever efforts are undertaken to weatherize such structures. A major drawback with the retractable bollards of Dickinson and most others, however, is the inherent complexity and cost associated with these types of device.
Thus, there exists a long-felt, yet unfulfilled need for bollards which may be expediently and reliably collapsed in an emergency, yet secure a transitway from unauthorized traffic.